#define _CRT_SECURE_NO_WARNINGS 1

#include "Stack.h"

void STInit(ST* ps)
{
	assert(ps);
	ps->a = NULL;
	ps->top = 0;
	ps->capacity = 0;

}


void STDestroy(ST* ps)
{
	assert(ps);
	free(ps->a);
	ps->a = NULL;
	ps->capacity = ps->top = 0;

}


void STPush(ST* ps, STDataType x)
{
	assert(ps);

	if (ps->capacity == ps->top)
	{
		STDataType newcapacity = ps->capacity ==  0 ? 4: (ps->capacity)* 2;
		STDataType* tmp = (STDataType*) realloc(ps->a,sizeof(STDataType)* newcapacity);
		if (tmp == NULL)
		{
			perror("realloc fail");
			exit(-1);
		}

		ps->a = tmp;
		ps->capacity = newcapacity;

	}
	ps->a[ps->top] = x;
	ps->top++;

}

void STPop(ST* ps)
{
	assert(ps);
	assert(ps->top > 0);

	ps->top--;

}


STDataType STTop(ST* ps)
{
	assert(ps);

	assert(ps->top > 0);

	return ps->a[ps->top-1];
}

int STSize(ST* ps)
{
	assert(ps);

	return ps->top;

}

bool STEmpty(ST* ps)
{
	assert(ps);

	return ps->top == 0;
}
